If Dufay's Missa L'homme armé (from the 1460s) had survived anonymously, one could easily believe it to be the work of a breathtakingly ambitious young composer. On the face of it, the Mass appears to be the work of a man determined to impress, keen to show that he is never lost for ideas, that he will not borrow any convention without turning his handling of it into a commentary of some kind - in short, a man who will always go one step beyond convention. The almost over-confident message seems to be: whatever others have done, I can do it better.

Yet Dufay was not a young man when he wrote the Missa L'homme armé. In fact he was almost certainly in his sixties, by which time illness had already forced him to turn his mind to his imminent death and the salvation of his soul. Unlike younger composers such as Regis, Caron, and Busnois, who were struggling in low-paid and onerous choirmasterships, Dufay was a wealthy ecclesiastical dignitary at one of the most prestigious establishments in Northern France: Cambrai Cathedral. He had been a musical celebrity ever since he had written his first motets in the 1420s and produced that astonishing series of state motets in the 1430s (including Supremum est mortalibus bonum). These early works had evidently become something of a legend, as they were still being copied and performed thirty years after their composition.

Yet the ageing Dufay was clearly not content with his legendary status alone, nor was he particu1arly wedded to the older styles in which he had once proved his international leadership. In the Missa L'homme armé he seems intent to prove (perhaps somewhat like the serialist Stravinsky of the 1950s) that his reputation had never depended on any particular stylistic idiom, but rather on his ability to carry every idiom to a plane of unprecedented artistic perfection. That intention - for a man who had little left to prove in this world (and might at that stage have been more concerned with his record in the next) - is no less remarkable than his undiminished artistic ability.

The Missa L'homme armé seems to have become a popular and successful work. It survives in four manuscripts (a large number for any 15th-century Mass), three of which were copied in Italy and one, remarkably, in Scotland, at a time when no other Continental works seem to have been appreciated in the British Isles. More importantly, in 1477 (three years after Dufay's death), the chief music theorist of the time held up the Missa L'homme armé as an outstanding example of the aesthetic principle of varietas ('to be thoroughly imitated').

That aesthetic principle may be hard for us to appreciate today, since the Missa L'homme armé moves entirely within the musical horizon of the 15th century, whereas the modern ear is conditioned mostly by what lay beyond that horizon. Given the astonishing range of musical styles to which we are exposed every day, Dufay's setting may strike us initially as homogeneous rather than varied, and perhaps as virtually indistinguishable from any other 15th-century Mass. It would take considerable effort to imagine the sensitive and discerning ear that would have been shaped by a lifetime spent singing, composing, and listening within the same horizon. Given the relative homogeneity of the musical idiom, variety would have been detectable in the smallest detail - the very level on which Dufay sought to impress his contemporary audience most.

Beyond that, we are heirs to a musical tradition that values unity (whether cyclic or motivic) more than variety. If modern analysis is meant to foster musical understanding (and thereby perhaps to enlighten musical experience), its very methods of reduction and distillation seem to predispose us to an understanding that is very different from that valued in the 15th century. In the Missa L'homme armé Dufay seems to have been concerned to create a fundamentally irreducible variety of kaleidoscopic detail in which moments are to be relished rather than eliminated in search of some deeper structure. To be sure, there is an underlying structure to the Mass in its recurring cantus firmus (the well-known L'homme armé song which opens this disc). Yet artistically that structure neither guarantees nor explains the quality of the work. Faced with a composition that places all musical significance in the individuality of each moment, our analytical tools are powerless, yet our ears await a feast of musical delight.

Oxford Camerata The Oxford Camerata was formed by Jeremy Summerly in order to meet the growing demand for choral groups specializing in music from the Renaissance era. It has since expanded its repertoire to include music from the medieval period to the present day using instrumentalists where necessary .The Camerata has made several recordings for Naxos, and future plans include discs of music by Gibbons and Weelkes.

Jeremy Summerly Jeremy Summerly was a choral scholar at New College, Oxford, from where he graduated in 1982. For the next seven years he worked as a Studio Manager with BBC Radio and it was during this time that he founded the Oxford Camerata. In 1989 he left the BBC in order to join the Royal Academy of Music as a lecturer in the department of Academic Studies and in 1990 he was appointed conductor of Schola Cantorum of Oxford. He has recently signed a long-term contract with Naxos to record a variety of music with the Oxford Camerata and Schola Cantorum of Oxford.